I've been running DNN 311 for a year or so now, with nearly no problems.  But recently changes made to anything on the site have quit saving or updating for a long period, or takes a while to show up.  This includes pages, modules, roles, users.  If we make a change, it may show up immediately, or maybe 20 minutes later after multiple refreshes.  And sometimes after the change appears, it'll revert to old on next refresh.  We're using DNN for a school system web site, and it's a pain to teach folks to use it when their changes won't take.  I've tried changing from multiple browsers, thought IE7 might be to blame.  I've also dumped cache on local machines and on cahing firewall / proxy server.  Reindexed / error checked database.  Nothing showing in logs, other than messages saying changes have been made, after they show.  Not logged immediately.   Any help??... Please & Thanks...

DNN 3.1.1, WIndows Server 2003, SQL 2000 Std., .NET 1.1.4322.